Telephone system



Nov. 22, 1932.

A. E. CASWELL.

TELEPHONE SYSTE! Filed May 4. 1951 5 Sheets-Sheet l IFITLEFTEFM HfihurEdward Easuzall Nov. 22, 1932. A. E. CASWELL 1,888,307

TELEPHONE SYSTEM Filed May 4, 1931 '3 Sheets-Sheet 2 lbl l 8 Zbl jrtlYEZ

8 I Irma??? FlFThur Edward 125.511.1511

Nov. 22, 1932. A. E. CASWELL TELEPHONE SYSTEM Filed May 4, 1951 3Sheets-Sheet 3 rm H'Fl'hur Edward Casmell Patented Nov. 22, 1932 UNITEDSTATES PATENT OFFICE.

ARTHUR EDWARD CASW EIQL, OLEv LIVERPOOL, ENGLAND, ASSIGNOR T0 ASSOCIATEDTELEPHONE & TELEGRAPH COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OFDELAWARE TELEPI'IONE SYSTEM Application .filedMay 4, 1931, Serial No.534,829, and in Great Britain June 18, 1930.

The present invention relates to telephone systems and is moreparticularly concerned with arrangements for applying routine tests tovarious pieces'of apparatus, in accordance with what is now usualpractice, with the objectof discovering any faults which may occur andallowing them to be attended to before they result in annoyance tosubscribers. The chief object ofthe invention is to provide an improvedarrangement permitting the satisfactory routining of the apparatuslocated at the incoming end of a two-wire junction to be effectedwithout causing any appreciable interference to ordinary service.

It may/be stated generallythat, as regards the testing of apparatushaving associated with it a special test conductor, it is possible togive'the routiner direct access to this conductor and thus ensure thatthe routiner only seizes the apparatus in question when it is notalready in use and that it is then busied against seizure from itsnormal means of access during the time the test is being carried outthereon. In the case of apparatus at the incoming end of two-wirejunction lines, however, this procedure cannot be followed and there isthus a danger that while routining is taking place a subscriber willseize the junction since it is unguarded at the outgoing end. It hasbeen suggested to open the speaking conductors and apply a warning tone,for instance busy tone, to the junction during the test, but this is notentirely satisfactory in any event and moreover'if the junction orcircuit were faulty the routiner might be associated with it for anappreciable time during the whole of which period'the junction would beunguarded at the outgoing end. Hence, if the junction were an earlychoice in the bank of the hunt ing switch seized by the subscriber, hemight be unable to complete his connection as each time he called hewould be connected to the same faulty junction or circuit.

According to one feature of the invention, arrangements are made forgiving access from the routiner to the outgoing end of the junction anddefinitely busying it there while the'test is proceeding so that thereis no danger of a subscriber being unable to get past the junction undertest if it should be found fault-y.

According to another feature of the invention, the control of theapparatus at'the outgoing end of the group of junctions is effected overone of the junctions ofthe group, this junction being only busied tonormal service while routine tests are actually taking place.

The arrangement according to the invention, moreover, tests also for thecontinuity of the junction itself which is naturally not attempted inthe arrangement. where the leads are opened during the test. a

The invention will be better understoo from the following descriptionofone method of carrying it into effect which should be taken inconjunction with the accompanying drawings comprising Figs. 1 to 3 whichare intended to fit together with Fig. 2 on the right of Fig. 1 and Fig.3 below Fig. 2.

Fig. 1 illustrates the apparatus located at the exchange from which thegroup of junctions concerned are outgoing,

Fig. 2 shows the incoming ends of the junctions and Fig. 3 shows theauxiliary equipment associated with the routiner.

Itshould be mentioned that certain of the relay contacts shown in Fig. 3are assumed to be carried by relays associated with a routiner of knowntype which are not shown and while this will be specially referred to asthe de scription'proceeds, the contacts have been dis.- tinguished byenclosing them in a small rectangle.

It is assumed that the two junctions shown are accessible at theoutgoing end from a hunting switch JF which may be of either numericalor non-numerical type, that is to say, it may perform only a huntingoperation or it may first be set by impulses. It is also assumed that atthe incoming end of each junction a line relay such as relay 1A isconnected across the two speaking conductors l0 and 11 eitherpermanently or temporarily, and the operation of this relay energizes aslow relay 113, not shown, which then at armature Zb-l applies potentialto a guardor release trunk conductor 12 which is extended forward tosucceeding switches and also to the test bank of the access switches,such as AS, Fig. 3, associated with the routiner.

As regards the junction to be used for control purposes, which in thearrangement shown is the first choice of the hunting switch JF, butwhich in some circumstances might more satisfactorily be the lastchoice, the two conductors 13 and 1 1 of this junction are arranged topass through contacts 121 and p2 respectively of a relay 1? in theauxiliary equipment associated with the control junction, this relayenergizing and switching through the said conductors when the junctionis seized for normal purposes. The conductors 15 and 16 of the samejunction also pass through contacts M1 and N2 of relay RT,

ig. 2, at the incoming end to enable the proper controls to beexercised. As regards the remaining junctions in the group however, thecontrol equipment is merely tapped oil at the two ends and thus wiringis simplified and apparatus saved.

When a test is to be made it is first necessary to take into use thecontrol junction and it is clearly impossible in this case to obtainaccess to the distant end without unjustifiably complicating theapparatus so that for this junction alone it has to be assumed that ifit is not marked busy at the incoming end it is free at the outgoing endalso. In case, however, the junction or outgoing circuit should be insome respect faulty and a subscriber should be connected thereto, theseizing of the junction for routining purposes will connect up numberunobtainable or busy tone to the junction conductor 16, and subsequentlythe junction will be busied so that the subscriber on replacing hisreceiver when he hears the tone will be enabled to take into use anotherjunction when he makes a further attempt to set up a call.

The routiner itself may be arranged to perform any desired functionsdepending upon the precise nature of the apparatus connected to thejunction at the incoming end.

When the routining operation is to be initiated, the usual start keywill be operated and when the access switch AS, Fig. 3, connects withthe first junction of the group extending from the particular distantexchange under consideration, that is, in the arrangement shown, thecontrol junction, relay SL, which is individual to that group ofjunctions, will be energized by earth transmitted over conductor 17. Ifthis junction is already in use, the line relay 2A will be operated,resulting in the operation of the release relay 2B, not shown, in thewell-known manner. At armature 2b1 earth will be connected to therelease trunk conductor 18 for this circuit and therefore, to theappropriate contact on the routiner access switch private bank withwhich wiper 3c of the access switch AS will be in engagement.

The routiner will therefore wait until the junction becomes tree andwhen this occurs relay PE, not shown, in the routiner will operate itsarmature p01 and this will energize relay RT which is also individual tothe particular group of junctions under consideration. Relay RTthereupon at armature rt?) completes a lockin g circuit for itself, atarmature r254 applies busy tone by way of the busy tone transformer BT Tinterrupter I and con- P denser QA to conductor 16 and at armatures M1and M2 disconnect-s the junction from its normal circuit and connectsearth to the conductor 15 over conductor 22, in order to energize relayLA, Fig. 1, at the distant exchange over armature p1. Relay LA inoperating, at armature lal energizes relay B which at armature blprepares a step-on circuit for the distributor switch SD, at armature b2applies earth over conductor 21 to the bank of the hunting switch J F inorder to busy the junction, at armature b3 prepares a test circuit forthe junctions to be routined later, at armature b4 applies numberunobtainable or busy tone over condenser QB to conductor 13, and atarmature lights the supervisory lamp corresponding to the junction overwiper 1b and corresponding bank contact of the distributor switch SD.

The routine test now takes place on the apparatus associated with thecontrol junction and when it is completed certain circuit operationstake place in the routiner which result in the energization of relay TF.This relay thereupon at armature tfl opens the circuit of relay LA, Fig.1, for a sutlicient period to allow the distributor switch SD to stepits wipers to the next junction due to the circuit completed from earth,armatures 1(11 and b1, winding of the driving magnet SDDM of thedistributor switch to battery, if desired through the winding of alow-resistance supervisory relay in known manner.

Relay H, Fig. 1, is of sufiiciently low resistance to constitute a busymarking and if the next junction is already busy, relay H will beshort-circuited and thus be unable to operate. When, however, thejunction becomes free, relay H operates from earth,

armature b3, winding of relay H, resistance YA to battery, and atarmature 71.1 completes the following circuit for relays LB, Fig. 1, andL, Fig. 3: earth, right-hand winding of relay L, left-hand winding ofrelay L, armatures tal, all, and 5Z2, conductor 23, armature r62,conductor 16, armatures 712 and 72,1, winding of relay LB to battery.Relay L only is operated in this circuit and it thereupon short-circuitsits high resistance left-hand winding over operated armatures Z1 and7362 which latter armature will be operated at this time if the test isproceeding satisfactorily. The consequent reduction of resistance in thecircuit permits relay LB to opcrate, and at armature Zbl it completes acircuit from battery, winding of relay LG, armature Z61, wiper 2b andbank contact of the distributor switch SD, junction conductor 11, bankcontact and wiper 2c of the access switch AS, Fig. 3, armature Z3,winding of relay TB to earth. The current in this circuit will besufficientto operate relay LC but not relay TB and the former thereuponcompletes a circuit from earth, armature Z01, wiper lb and bank contactof switch SD, junction conductor 10, bank and wiper Z0 of switch AS,armature Z2, right-hand winding of relay TA to battery. Relay TAthereupon at armature m3 locks up to the routiner test earth overconductor 26, at armature m1 brings down relay L and at armature m2releases relay PF which by connecting earth to lead 24 permits the testto proceed.

It will be noticed that the connections just described constitute a testfor synchronism between the distributor switch SD at the distantexchange and the access switch AS associated with the routiner at theincoming exchange since, if the latter switch should be associated withjunction other than that with which the wipers of the distributor switchSD are connected, both relays TA and TB will be operated if the junctionconductors are looped and neither if the junction is not in use.In'these circumstances, the alarm relay AL connected to conductor 25will be operated from routiner test earth over conductor 27, armatures5Z4, m2 and 661 and the consequent lockin up of relay PF over eitherarmature we or armature tb2 will prevent the test being continued byremoving earth from the conductor 24 at armature pfl. It should bepointed out that the earth supplied over armature $7 1 is alsodisconnected from conductor 24 at this time since relay SR, not shown,is operated at the conclusion of the test on the control junction andremains operated until all junctions extending from the exchange underconsideration have been routined.

At the conclusion of each test, relay TF associated with the routinerwill operate its armature tfl momentarily thus allowing relay LA at thedistant exchange to release for a period sufiicient to advance thewipers of the distributor switch SD one step. The access switch AS atthe main exchange is also advanced one step and the test on the junctionconnected with then proceeds as soon as relay TA associated with theroutiner has de-energized on the return of the routiner to normal andrelay H in the distant exchange has operated in response to the idlecondition of the junction.

It will be appreciated therefore that a very simple arrangement has beendevised whereby the routine testing of apparatus associated withjunction lines at the incoming end may be placed on a satisfactory basiswith the use of only a small amount of additional equipment and moreoverwithout resulting in any appreciable increase of the testing time.

What I claim as new and desire to secure by Letters Patent is: s

1. In a testing system, a first station, a second station, a pluralityof junctions originating in the first station and terminating in thesecond station in automatic switches, all of said junctions beingaccessible at the first station for regular service to the secondstation, routine testing equipment at the second station for routinetesting saidautomatic switches and having means for successivelyassociating it with said switches, and. means at the first stationcontrolled by said equipment over a certain one of said junctions formarking each junction busy to its normal means of access at the firststation while said equipment is testing the switch in which thatjunction terminates.

.2. In a testing system, a first station, a second station, a pluralityof groups of junctions originating in the first station and terminatingin the second station, all of said junctions being accessible at thefirst station for regular traffic to the second station, testingequipment at the second station for testing a junction and having meansfor associating it with each group of junctions separately andconnecting it successively to the terminating ends of the junctions ofeach group, and means at the first station individual to each group ofjunctions for cooperating with said testing equipment to perform thetests on each junction, each individual means controlled over a certainjunction of the associated group by said equipment.

3. In a telephone system, a branch exchange, a main exchange, aplurality of twowire junctions originating in the branch exchange andterminating in the main exchange, all of said junctions being accessibleat the branch exchange for regular trafiic to the main exchange, testingequipment at the main exchange for testing the continuity of both wiresof each junction, a distributor switch controlled by the testingequipment for successively connecting the equipment to the terminatingends of said junctions, and a switch at the branch exchange controlledover a certain one of said two-wire junctions by the testing equipmentat the main exchange to connect potential to the originating end of eachjunction while the testing equipment is connected to the terminating endin order that said equipment can test the continuity of each junction,said switch at the branch exchange marking each junction busy to itsnormal means of access while it is being tested.

4. In a telephone system, a. branch exchange, a main exchange, a groupof junctions originating in the branch exchange and terminating in themain exchange in automatic switches, all of said junctions beingaccessible at said branch exchange for regular traflic to said mainexchange, testing equipment at said main exchange for testing thefunctions of said automatic switches, a distributor switch operatedbysaid equipment for connecting it to said automatic switchessuccessively, means at the main exchange for associating said equipmentwith one of said junctions, said equipment thereupon functioning toperform its tests on said automatic switches, a junction busying switchat the branch exchange, and means associated with said one junction atthe branch exchange and controlled over said one junction by saidequipment for operating said busying switch in synchronism with saiddistributor switch to thereby busy the originating end of each junctionto its normal means of access while said equipment is testing theautomatic switch at the terminating end of the same junction.

5. In a testing system, a first station, a second station, a pluralityof groups of junctions originating in the first station and terminatingin the second station, all of said junctions being accessible at thefirst station for regular traffic to the second station, testingequipment at the second station for test ing a junction and having meansfor associating it with each group of junctions separately andconnecting terminating ends of the junctions of each group, means at thefirst station individual to each group of junctions for cooperating withsaid testing equipment to perform the tests on each junction, eachindividual means controlled over a certain junction of the associatedgroup by said equipment, and means at said branch exchange for visuallyindicating the connection of said equipment to the automatic switch ofeach junction.

6. In a telephone system, a branch exchange, a main exchange, a group ofjunctions extending from said branch exchange to said main exchange, allof said junctions being accessible to said branch exchange for regulartrafiic to said main exchange, testing equipment at said main exchange,controlling apparatus for said equipment and associated with one of saidjunctions at the main exchange, auxiliary controlling apparatusassociated with said one junction at said branch exchange, means at saidmain exchange for connecting the control apparatus thereat to said onejunction, said controlling apparatus and said auxiliary controllingapparatus thereupon functioning to connect said testing equipment toeach junction of the group to perform a test thereon, and means at saidbranch exchange operated by said auxiliary controlling apparatus formarking each junction busy to its normal means of access while saidtesting equipment is connected thereto.

it successively to the tur 7. In a telephone system, a branch exchange,a main exchange, a group of junctions originating in the branch exchangeand terminating in the main exchange in automatic switches, all of saidtrunks being normally accessible at the branch exchange for regulartraffic to the main exchange, routine testing equipment at the mainexchange for routine testing said automatic switches and having adistributor switch operated thereby for connecting the equipmentsuccessively t0 the terminating ends of said junctions to give theequipment access to said automatic switches, means for associating saidequipment with a certain one of junctions at the main exchangeindependently of said distributor switch to cause said equipment to testall of said automatic switches, means at the branch exchange associatedwith said certain junctions for marking said certain junction busy toits normal means of access while said equipment is associated therewith,and a busy-marking switch at the branch exchange controlled over saidcertain junction by said equipment and in synchronism with saiddistributor switch for marking each junction busy to its normal means ofaccess at its originating end while said equipment is connected to itsterminating end.

In testimony whereof I aflix my signa- ARTHUR EDVVABD CASWELL.

